Color television



L. W. PARKER COLOR TELEVISION Aug 2, m9.

Filed April 24, 1946 INVENTOR. ZUU/S PAR/(L7? Patented Aug. 2, 1949 COLOR TELEVISION Louis W. Parker, Jackson Heights, N. Y., assignor to Federal Telephone and Radio Corporation, New York, N. Y., a corporation of Delaware Application April 24, 1946, Serial No. 664,487

7 Claims.

This invention relates to television systems and,

more specifically, to an improved light source and optical apparatus for television image reproduction.

Principally, the present invention is directed to methods and means for increasing the light efliciency of television picture reproducing systems of both the black and white and multi-color classes. This result is achieved b the elimination of light waste due to filter action, by the increased lengths of time during which the television pictures are observable with the human eye, by the utilization of a cathode ray tube face capable of transmitting with little loss and distortion the light generated within the tube, and by a highly efiicient light producing arrangement in which ultra-violet light is employed to generate visible light.

It is important to note that conventional color television receivers operating, for example, on a tri-color basis theoretically utilize only one third of the available light at any instant; practically, the efficiency is even less when it is considered that the colors on the screen of the television tube are rarely represented in exactly correct proportions and that the efficiency of the filters is not 100%. Also, persistence eifects involved in the usual type of television receiver are detrimental to the resultant images. An additional disadvantage encountered with the use of the majority of present television systems is that both the intensity and angle of spread of light generated within the picture tube are reproduced on a the outside surface of the tube face with considerable loss. These disadvantages are very effectively excluded from the apparatus disclosed herein.

It is one object of this invention, therefore, to provide method and means for increasing the light eiliciency of television image reproducing systems, particularly of color television systems.

A second object is to provide a multi-color television picture reproducing system wherein color filtering apparatus-is not required and wherein light waste due to filtering action is thus eliminated.

Another object is to provide a television picture reproducing system wherein a highly efficient television tube screen and high persistence auxiliary light-producing screens are employed to im-v prove the light intensity and flicker characteristics of the resultant images.

Further, it is an object to provide a picture reproducing system, for television receivers, in which ultra-violet light generated on the face of a cathode ray tube causes visible radiation of desired wavelengths from surfaces having the reultra-violet light under electron bombardment," calcium tungstate being a representative mate- Y rial. External to the tube are located a series of phosphor-coated transparent screens mounted on a rotatable drum, each of the screens being capable of producing visible radiation of desired colors when excited with'ultra-violet rays from the tube. Due to the rotation of the drum, successive lines of the picture, which are in substantially the same position on the tube face are properly displaced when they appear on the phosphor-coated screens. The drum rotation is additionally synchronized such that one complete frame of a picture may be reproduced on only a single phosphor-coated screen, and such that this screen will produce the color of radiation corresponding to the color represented by the frame being traced at any instant. Th viewing arrangement used with this system includes equipment for making the rotating picture frames appear stationary to the observer for certain lengths of time.

The objects and features disclosed above should be made more clear and. a fuller understanding of the entire invention should be obtained from the following detailed description and discussion of one preferred embodiment, reference being had to the drawings in which:

Fig. 1 is a view, partially in section and elevation, of a multi-color picture reproducing apparatus associated with a cathode ray tube in accordance with the color television system of this invention; and

Fig. 2 is a left side view of the equipment diagrammed in Fig. 1.

Each line of a television picture is-reproduced by a cathode ray'tube l, the face 2, of the tube being coated internally with a layer of material 3, which emits ultra-violet light in response to electron bombardment. A narrow window 4, constructed of some material translucent to ultraviolet light, quartz for example, is provided in the tube face, permitting light generated by the material 3, to be transmitted therethrough. The dimensions of the quartz window may be those of .a narrow rectangular parallelepiped since the horizontal picture lines are all traced in substantially the same position on the tube face.

Transparent curved screens 5, are attached to a rotatable drum 6, such that different screen sections are successively rotated past the quartz window 4, when the drum is turned by driving means, shown as a shaft 1, in this embodiment. Individualiscreensiare'surfaced, preferablyiprrmher sides adjacent the tube face, with phosphor materials 8, 9, and I0, which emit visible light of different wavelengths. A typical tri-color tele-- vision system might employ phosphors whichupm r duce red, green, and blue radiations.

The driving shaft I, must-revolve drumyfifiatn" foregoing principles, provided the proper screen coating materials are used, and a direct viewing system may be employed also. It should thus be apparent that many changes in the arrangement shown may be made by those skilled in the art without departing either in principle or scope from the present invention, and although only a sin glelpreferred :iembodimentthasnben diagrarnmed and "describedy the entire invention should not be considered limited thereby.

I claim:

1.,-.A.=method for reproducing color television images on light responsive surfaces which compriseseproducinglpictune lines in ultra-violet light the synchronous speed at whichonei'frame ofta 'at a rela tivelygfiiied position with an intensity picture will be traced on one screen'attached to the drum, and an additional phasingimustabeisaw V cured in order that the screen with the proper. color-radiating surface may be rotated past th" quartz window during anyi frame tracing interval. Rbtative snotiomnwith rtheeequi-red synchnmism 3. may bvimparteckto thel drivirrgashnitzbyzanyrot: the many wellilkn'cwmteleyisiormnoti vosystems, oi whlch-ananduntiorrmiotmosmmhrorfizeziwitlila proportional to'theintensity of an electron beam impiga-ging ons-said. surfaces, converting at said surfaces said ultra-violet light into visible light of different wavelengths with variations in intensity corresponding to said ultra-violet light impiri ngtthermnnandumoidng said :surfacese relae tive'etmdzlrezaelatively; fixed:- position so: rthatnsuccessivnvisibleilines 0 53a picturerziramel are. spaced..- correctly on said screens and such that certainn phon ic motdr orunagneticzbrame ismepresentativze: ea5picturearazmeselarevreproduced only -.ons.screens Pieturesitraced on thaf lmmdfscmimstfibafi made tmappeaa' startionamrfta anmbseraremzandz; tl'fei arrangementsshown 'imtlrei accompanying figs?- ures is typical .ofiithose which may: be appliedstow emittingrvisilrlenzlightc ofz-desiredwavelengthszs.

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tinction, when screen persistence issofzsuflicient. duratiom; Pieture-efr'amesssappearinggon ;the S0288}! is neeii'ai notlrcompletely- :1 disappeareruntila nearly a womplete1revolutiomof:theidrumlli,shast.- beemaccommishemzi.

Onllyl a ssinglelvliner appears lon ltheoi ace {anthers cathode ray tube I, at anyvinsta-ntn.Thismenessimtateszitheseuserofzshort persistenceanaterials Jar emitting'gfltra-rviolet lighti-fromsthe tube.-.face .4

some means-,snotrillustratedamaysbereutilized :to-sapply a vertical sweep to the electrombeamrandeto-e obtainza rotsmy motionsofrscreens iewhichicompensates for the line displacementmrhthe.etubem rangementi' acconiing. ;to..claim:2,;,whereint said: 1 coatingifor said itubeaiaice comprises: a deposit: oi;- caiciumztungstate'le.

451A 9101 ;televisi.on .ipicture-srcproducing- 1-1pm;-

55.?rangementucommising {a mathode: ray tubemapa.

fa'cezs; An-additionalladvantaglglohthisinvention -13 mm gegponsimflla; ultra-wicket zlightrimpingsg hitherto (not. appanentzmor mentioned-.isqthats a rectangulampicture mayvbeiseeureckrhavingassitsw smallersrdimensiondahe ileng'tmpft-thenline ,crrwthe s facezeof: therecathodeieram tubeze Anconsiderableze ing thereon, means for moving said screenszandz coatingsobf'orer said tubez rface iaoienablei success siveztelelvisionirpioturetalinesito' be aeproduceck om:- SQIiflTZTSOIBGHSEEWitIIZ thczzrequired rspacing and atom ecenomynimztubel sizesforrra :desired rectangulanr* M mh iw reproduced nnscreensg,

coiornirnazgmcnay therefore be: realized.

The: emhodmrerrt asproposnd'relatesatoza multisi colokrprnjeotiu'mztype televisim-rrsystemz however; iti shoulcl be understood-:th'aflrza zblackcandmrhiteie havingsrdesired vislble light wavelehgth characteristics, and prismaticmneans for causin'g the pictureuframes-sto appear"stationary :to' 'an observeie'duringi certain time intervals? image may bewbtazlned in accordance with tlie e 5. :Aacolo'r'rtelevisiorr picture reproducing anrangement according to claim 4, further comprising optical means for projecting the stationary picture frames to a viewing screen.

6. A system for reproducing color television pictures, comprising a cathode ray tube having a screen at one end thereof, means for producing television picture lines in ultra-violet light in substantially one position on said screen, movable screens positioned externally of said tube for reproducing picture frames according to their visible light wavelengths, coatings for said external screens capable of generating and emitting visible light of certain wavelengths in response to ultra-violet light falling thereon, driving means for moving said screens past said one position to allow successive picture lines of ultra-violet light to impinge on said coatings with a desired spacing, and rotatable prismatic means responsive to said driving means for causing said pictures to appear stationary for a predetermined time.

7. A color television image reproducing system, comprising a cathode ray tube having a face capable of transmitting ultra-violet light and a coating on said face for generating ultra-violet light in response to the electron beam impinging thereon, said tube being capable of producing picture lines in substantially one position on said face, a plurality of movable screens for reproducing REFERENCES CITED The following referenlces are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,319,804 Dyer May 25, 1943 2,336,134 Szegho Dec. 7, 1943 FOREIGN PATENTS Number Country Date 105,944 Australia Dec. 8, 1938 490,029 Great Britain Aug. 4, 1938 517,483 Great Britain Jan. 31, 1940 

